A Giant Mucinous Adenocarcinoma Arising within a Villous Adenoma of the Urachus: Case Report and Review of the Literature

Abstract

We present an exceptional case of a giant urachal tumor, consisting of both villous adenoma and mucinous adenocarcinoma of the urachus. The tumor was incidentally discovered during investigations for renal failure. Initial transurethral biopsies showed only a villous adenoma of the urachus. Although the biopsies showed no malignancy, a radical cystoprostatectomy and broad excision of the urachus and umbilicus were performed. At the same time, a bilateral nephroureterectomy was performed because of reflux-nephropathy and renal failure. The indication for surgery was based on the typical imaging aspects, raising the suspicion of an underlying urachal adenocarcinoma (size and location). Indeed, at final histopathology a concomitant well-differentiated adenocarcinoma of the urachus confined to the urachal mucosa was found. The patient remained free of disease for 50 months of follow-up. Only three previous cases of urachal adenocarcinoma associated with villous adenoma have been described.

Figure 1

Contrast enhanced CT-scan of the abdomen (prone position), showing a large bladder mass, protruding the bladder and almost completely filling up the bladder lumen.

Figure 2

(a) Villous adenoma of the bladder with complex branching papillary structures, that are distended due to the presence of the exophytic mass in the lumen. There is no invasion into the underlying bladder wall ‘ (Hematoxylin Eosin stain, original magnification 50×) Inset: Higher magnification shows that the fibrovascular stalks of the adenoma are lined by pseudostratified mucinous epithelium with only mild degree of anisokaryosis. (Hematoxylin Eosin stain, original magnification 200×), (b) Urachal mucinous adenocarcinoma characterized by small sheets and nests of columnar mucinous cells floating in extracellular mucin. (Hematoxylin Eosin stain, original magnification 50×), (c) The cysts are lined with urachal mucinous adenocarcinoma with invasion in the bladder wall. (Hematoxylin Eosin stain, original magnification 25×), (d) Detail of papillary projections coated with columnar mucinous cells with pseudostratification, nuclear hyperchromasia and crowding, and goblet cells. (Hematoxylin Eosin stain, original magnification 200×).